166720001 has 12 divisors (see below), whose sum is σ = 194156820. Its totient is φ = 142742880.

The previous prime is 166719997. The next prime is 166720007. The reversal of 166720001 is 100027661.

It can be written as a sum of positive squares in 2 ways, for example, as 3519376 + 163200625 = 1876^2 + 12775^2 .

It is not a de Polignac number, because 166720001 - 2² = 166719997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166720007) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 68831 + ... + 71211.

It is an arithmetic number, because the mean of its divisors is an integer number (16179735).

Almost surely, 2^166720001 is an apocalyptic number.

It is an amenable number.

166720001 is a deficient number, since it is larger than the sum of its proper divisors (27436819).

166720001 is a wasteful number, since it uses less digits than its factorization.

166720001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3824 (or 3817 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 166720001 is about 12912.0099519788. The cubic root of 166720001 is about 550.3799039181.

Adding to 166720001 its reverse (100027661), we get a palindrome (266747662).

The spelling of 166720001 in words is "one hundred sixty-six million, seven hundred twenty thousand, one".